This invention relates to the dividing of an amount of liquid into several portions in a precise, predetermined ratio, and particularly to apparatus for so dividing liquid.
During chemical analysis, it is often necessary to separate a precisely defined portion of a body of liquid from the remainder of the body. A pipette is the instrument conventionally employed for manually withdrawing an aliquot from a body of liquid to be analyzed, and automatic pipettes have been used in automatic apparatus for chemical analysis in which several aliquots often have to be drawn from the same body of liquid. Automatic pipettes satisfying requirements for high precision are relatively complex, and they are costly to build and to maintain in good working condition.
It is a primary object of this invention to provide apparatus capable of dividing an amount of liquid into a plurality of portions in a precise, predetermined ratio which apparatus is simpler than an automatic pipette and less costly to build and operate.
With this object and others in view, as will hereinafter become apparent, the invention provides a normally stationary support on which a bowl is mounted for movement about an axis of rotation. An axially extending wall bounds a cavity in the bowl capable of containing the liquid to be divided during rotation of the bowl. The wall is formed with a passage extending therethrough between a first orifice communicating with the bowl cavity and a second orifice spaced radially outward from the first orifice relative to the axis of rotation. When the bowl is rotated about its axis at adequate speed, the second orifice moves in a radial plane and discharges liquid by centrifugal force.
Several partition walls mounted on the support and transversely intersecting the afore-mentioned radial plane define therebetween receptacles on the support which are open toward the liquid-discharging orifice and each receive a portion of the discharged liquid. The several portions may be withdrawn separately from the several receptacles through suitable draining devices.